记裂齿鱼属(Perleidus)一新种

本文记述了在安徽和县发现的裂齿鱼属一新种——扬子裂齿鱼(Perleidus yangtzensis,sp.nov.)。根据其形态特征,与相近的种作了对比,认为和马达加斯加早三迭世的皮氏裂齿鱼(P.pivetcaui)最为接近。从而认为含鱼化石地层的时代为三迭纪或可能为早三迭世。

A NEW SPECIES OF PERLEIDUS FROM ANHUI

A Triassic perleidid fish described here was collected by Mr. Jiang Dunchao from He Xian, S. E. Anhui province. It is an anterior half of fish preserved in a sandy marl, but unfortunately its exact horizon is not clear. Judging from the characters of the fossil and the matrix rock in which the fossil is embedded, it probably belongs to the Qinglong group of Lower Triassic.This fish has moderately elongate-fusiform body. The length of head including opercular apparatus is slightly smaller than maximum depth of body. The head is comparatively short and its length is 42 mm. The maximum depth of body is 45 mm. The snout appears to be very obtuse. The orbits are very large and anteriorly placed. The suspensorium is almost vertical. The bones of the cheek region and opercular apparatus are indicated by impressions, exhibiting the characters of Perleidus. The preopercular is very large and has nearly straight anterior and posterior borders. The maxilla is of palaeoniscoid shape. The dentition is rather robust and consists partly of pointed teeth and partly of crushing teeth. The former are situated mainly in the anterior, the latter in the posterior parts of the jaws. The external skull-bones at least both maxilla and mandible ornamented with tubercles of enamel.The body is covered with thick rhombic scales with enamel, their posterior margins are obtusely serrated. The peg-and-sock articulations of scales on the anterior flank are well developed.From the characters of the fish described above, it is quite obvious that this fish belongs to Perleidus, and is most akin to Perleidus piveteaui Lehman in the size of head, inclination of suspensorium, short postorbital part of maxilla and the pattern of the opercular apparatus etc., but it differs distinctly from P. piveteaui in the following combination of characters: Ventral border of preoperculum not concave towards the rear. Postorbital part of maxilla very short, its length (distance between posterior extremity of maxilla and vertical passing anterior border of preoperculum) less than third of total length of maxilla. Maxilla with relatively low postorbital part and slightly convex dentigerous border. External skull-bones with prominent tubercles of enamel. The exposed area of scales on the anterior flank with longitudinal ridges and grooves running to the postterior border. It differs distinctly from all known species. Therefore, a new species Perleidus yangtzensis is established.Perleidus is a Triassic fish which occurred in the lower Trias of Madagascar, Greenland, Spitzbergen and in M.-U. Trias of Europe and in Trias of W. Africa. It is also found in the Triassic deposits of China. All of the facts stated above showed that Perleidus had a world-wide distribution during the Triassic period.